1. Field of the Invention
The present general inventive concept relates to a hard disk drive, and more particularly, to a hard disk drive which can precisely and reliably read and write data by locating a read/write head at a preset outermost position of a disk when an actuator arm contacts a crash stop.
2. Description of the Related Art
Hard disk drives (HDDs) are devices to record data on a disk or reproduce data stored on the disk by using a read/write head. The HDDs are widely used as auxiliary memory devices of computer systems because of their fast access time to a large amount of data.
With the recent increase in TPI (tracks per inch) and BPI (bits per inch), the HDD has achieved a high capacity and its application field has expanded. Accordingly, there has been a request for development of compact HDDs which can be used for portable electronic products such as laptops, personal digital assistants (PDAs), and mobile phones. In addition to 2.5″ HDDs, compact HDDs having a diameter of about 0.8 inches (e.g., similar to a coin) have been actively developed and are expected to be used for mobile phones or MP3 players.
FIG. 1 is an enlarged perspective view of a portion of a conventional HDD 101 having a crash stop 170 installed thereto. FIG. 2 illustrates a defective shape of the crash stop that may occur during the manufacturing and/or installation of the crash stop of FIG. 1. FIG. 3 is a plan view illustrating a positional change that occurs when an actuator arm contacts the crash stop having the defective shape illustrated in FIG. 2.
Referring to FIG. 1, a conventional HDD 101 includes a disk pack 110 having a disk 111 for recording data, a head stack assembly (HSA) 140 having an actuator arm 143, where a read/write head 141 for recording data on the disk 111 and reproducing data from the disk 111 is installed at an end of the actuator arm 143, a voice coil motor (VCM) (not illustrated in FIG. 1) to pivot the head stack assembly 140, a printed circuit board assembly (not illustrated in FIG. 1), a crash stop 170 to inhibit the read/write head 141 from deviating from the outermost position of the disk 111, a base 160 on which the above elements are installed, and a cover (not illustrated in FIG. 1) to protect the components installed on the base 160.
The HSA 140 pivots around a pivot shaft 142 according to a driving force by the VCM. The HSA 140 includes the read/write head 141, the actuator arm 143 which pivots across the disk 111 about the central axis of the pivot shaft 142 so that the read/write head 141 can access data on the disk 111, a pivot shaft holder 144 to rotatably support the pivot shaft 142 and to which the actuator arm 143 is coupled and supported, and a bobbin (not illustrated) provided at the opposite side of the actuator arm 144 with respect to the pivot shaft holder 144 which is integrally formed with the actuator arm 143.
The rotation of the actuator arm 143 about the pivot shaft 142 enables the read/write head 141 to move to a predetermined position of the disk 111. In doing so, in order to prevent the read/write head 141 from being pivoted beyond the outermost position of the disk 111, a crash stop 170 is provided on the upper surface of the base 160. The conventional crash stop 170 illustrated in FIGS. 1 and 2 includes a housing 180 having a round column 183 in the upper portion thereof and a rubber ring 190 having a ring shape that is forcibly and detachably coupled to the round column 183 of the housing 180. With this configuration, the crash stop 170 can be easily manufactured by simply inserting the rubber ring 190 around the round column 183 of the housing 180.
However, in the conventional crash stop 170 of FIG. 2, the round column 183 of the housing 180 is substantially not perpendicular and may be leaning toward one side. Also, the rubber ring 190 may not be formed to have a uniform wall thickness so that a part of the rubber ring 190 is thicker than an other part thereof. Here, when the rubber ring 190 is coupled to the defectively shaped round column 183 of the housing 180 as illustrated in FIG. 3, a distance d2 from a side of a contact protrusion 143a of the actuator arm 143 to an imaginary center point of the crash stop 170 may be different from a preset distance d1. Thus, not only is the pivot radius of the actuator arm 143 changed, but also the read/write head 141 which is installed at an end portion of the actuator arm 143 may be deviated from the preset outermost position of the disk 111. As a result, the read/write head 141 may not be able to precisely and reliably read and write data.